/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/editors/mesh/editmesh_rip_edge.c
 *  \ingroup edmesh
 *
 * based on mouse cursor position, split of vertices along the closest edge.
 */

#include "MEM_guardedalloc.h"

#include "DNA_object_types.h"

#include "BLI_math.h"

#include "BKE_context.h"
#include "BKE_report.h"
#include "BKE_editmesh.h"
#include "BKE_layer.h"

#include "WM_types.h"

#include "ED_mesh.h"
#include "ED_screen.h"
#include "ED_transform.h"
#include "ED_view3d.h"

#include "bmesh.h"

#include "mesh_intern.h"  /* own include */

/* uses total number of selected edges around a vertex to choose how to extend */
#define USE_TRICKY_EXTEND

static int edbm_rip_edge_invoke(bContext *C, wmOperator *UNUSED(op), const wmEvent *event)
{
	ARegion *ar = CTX_wm_region(C);
	RegionView3D *rv3d = CTX_wm_region_view3d(C);
	ViewLayer *view_layer = CTX_data_view_layer(C);
	uint objects_len = 0;
	Object **objects = BKE_view_layer_array_from_objects_in_edit_mode_unique_data(view_layer, CTX_wm_view3d(C), &objects_len);

	for (uint ob_index = 0; ob_index < objects_len; ob_index++) {
		Object *obedit = objects[ob_index];
		BMEditMesh *em = BKE_editmesh_from_object(obedit);
		BMesh *bm = em->bm;

		BMIter viter;
		BMVert *v;
		const float mval_fl[2] = { UNPACK2(event->mval) };
		float cent_sco[2];
		int cent_tot;
		bool changed = false;

		/* mouse direction to view center */
		float mval_dir[2];

		float projectMat[4][4];

		if (bm->totvertsel == 0)
			continue;

		ED_view3d_ob_project_mat_get(rv3d, obedit, projectMat);

		zero_v2(cent_sco);
		cent_tot = 0;

		/* clear tags and calc screen center */
		BM_ITER_MESH(v, &viter, bm, BM_VERTS_OF_MESH) {
			BM_elem_flag_disable(v, BM_ELEM_TAG);

			if (BM_elem_flag_test(v, BM_ELEM_SELECT)) {
				float v_sco[2];
				ED_view3d_project_float_v2_m4(ar, v->co, v_sco, projectMat);

				add_v2_v2(cent_sco, v_sco);
				cent_tot += 1;
			}
		}
		mul_v2_fl(cent_sco, 1.0f / (float)cent_tot);

		/* not essential, but gives more expected results with edge selection */
		if (bm->totedgesel) {
			/* angle against center can give odd result,
			 * try re-position the center to the closest edge */
			BMIter eiter;
			BMEdge *e;
			float dist_sq_best = len_squared_v2v2(cent_sco, mval_fl);

			BM_ITER_MESH(e, &eiter, bm, BM_EDGES_OF_MESH) {
				if (BM_elem_flag_test(e, BM_ELEM_SELECT)) {
					float e_sco[2][2];
					float cent_sco_test[2];
					float dist_sq_test;

					ED_view3d_project_float_v2_m4(ar, e->v1->co, e_sco[0], projectMat);
					ED_view3d_project_float_v2_m4(ar, e->v2->co, e_sco[1], projectMat);

					closest_to_line_segment_v2(cent_sco_test, mval_fl, e_sco[0], e_sco[1]);
					dist_sq_test = len_squared_v2v2(cent_sco_test, mval_fl);
					if (dist_sq_test < dist_sq_best) {
						dist_sq_best = dist_sq_test;

						/* we have a new screen center */
						copy_v2_v2(cent_sco, cent_sco_test);
					}
				}
			}
		}

		sub_v2_v2v2(mval_dir, mval_fl, cent_sco);
		normalize_v2(mval_dir);

		/* operate on selected verts */
		BM_ITER_MESH(v, &viter, bm, BM_VERTS_OF_MESH) {
			BMIter eiter;
			BMEdge *e;
			float v_sco[2];

			if (BM_elem_flag_test(v, BM_ELEM_SELECT) &&
			    BM_elem_flag_test(v, BM_ELEM_TAG) == false)
			{
				/* Rules for */
				float angle_best = FLT_MAX;
				BMEdge *e_best = NULL;

#ifdef USE_TRICKY_EXTEND
				/* first check if we can select the edge to split based on selection-only */
				int tot_sel = 0, tot = 0;

				BM_ITER_ELEM(e, &eiter, v, BM_EDGES_OF_VERT) {
					if (!BM_elem_flag_test(e, BM_ELEM_HIDDEN)) {
						if (BM_elem_flag_test(e, BM_ELEM_SELECT)) {
							e_best = e;
							tot_sel += 1;
						}
						tot += 1;
					}
				}
				if (tot_sel != 1) {
					e_best = NULL;
				}

				/* only one edge selected, operate on that */
				if (e_best) {
					goto found_edge;
				}
				/* none selected, fall through and find one */
				else if (tot_sel == 0) {
					/* pass */
				}
				/* selection not 0 or 1, do nothing */
				else {
					goto found_edge;
				}
#endif
				ED_view3d_project_float_v2_m4(ar, v->co, v_sco, projectMat);

				BM_ITER_ELEM(e, &eiter, v, BM_EDGES_OF_VERT) {
					if (!BM_elem_flag_test(e, BM_ELEM_HIDDEN)) {
						BMVert *v_other = BM_edge_other_vert(e, v);
						float v_other_sco[2];
						float angle_test;

						ED_view3d_project_float_v2_m4(ar, v_other->co, v_other_sco, projectMat);

						/* avoid comparing with view-axis aligned edges (less than a pixel) */
						if (len_squared_v2v2(v_sco, v_other_sco) > 1.0f) {
							float v_dir[2];

							sub_v2_v2v2(v_dir, v_other_sco, v_sco);
							normalize_v2(v_dir);

							angle_test = angle_normalized_v2v2(mval_dir, v_dir);

							if (angle_test < angle_best) {
								angle_best = angle_test;
								e_best = e;
							}
						}
					}
				}

#ifdef USE_TRICKY_EXTEND
found_edge :
#endif
				if (e_best) {
					const bool e_select = BM_elem_flag_test_bool(e_best, BM_ELEM_SELECT);
					BMVert *v_new;
					BMEdge *e_new;

					v_new = BM_edge_split(bm, e_best, v, &e_new, 0.0f);

					BM_vert_select_set(bm, v, false);
					BM_edge_select_set(bm, e_new, false);

					BM_vert_select_set(bm, v_new, true);
					if (e_select) {
						BM_edge_select_set(bm, e_best, true);
					}
					BM_elem_flag_enable(v_new, BM_ELEM_TAG);  /* prevent further splitting */

					changed = true;
				}
			}
		}

		if (changed) {
			BM_select_history_clear(bm);

			BM_mesh_select_mode_flush(bm);

			EDBM_update_generic(em, true, true);
		}
	}

	MEM_freeN(objects);

	return OPERATOR_FINISHED;
}


void MESH_OT_rip_edge(wmOperatorType *ot)
{
	/* identifiers */
	ot->name = "Extend Vertices";
	ot->idname = "MESH_OT_rip_edge";
	ot->description = "Extend vertices along the edge closest to the cursor";

	/* api callbacks */
	ot->invoke = edbm_rip_edge_invoke;
	ot->poll = EDBM_view3d_poll;

	/* flags */
	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;

	/* to give to transform */
	Transform_Properties(ot, P_PROPORTIONAL | P_MIRROR_DUMMY);
}
